Do you have new base, pigments, or additives in either ink?
I am assuming this is a brand new problem....
Sounds like some kind of wicking is happening. Potentially, the problem is a bad product. Or, of mixing in to much of an additive. Possibly a bad pigment batch...
Did the print cure out the same? Does it feel the same/look the same as all other waterbase prints?
Did it pass a wash test?